In current compact cameras, the position of the taking lens is automatically adjusted according to the subject distance as detected by a distance measuring device, and the exposure is automatically controlled according to the subject brightness as detected by a light measuring device, in order to obtain a good quality picture with a minimum of manual operation. The autofocus and automatic exposure control functions are performed using a microcomputer incorporated in the camera. In addition, a flash unit is known in the art which is automatically actuated to flash when the detected subject brightness is below a predetermined level.
In flash photography in which a flash unit is used as supplementary light for exposure, the diameter of the aperture, for example the diameter of the aperture at the moment when the flash unit flashes in case of a camera having a program shutter, which controls aperture selection as well as shutter speed, is ordinarily smaller than that in cameras without a flash unit under the same conditions. It is known in the art that the depth of field becomes greater when stopping down the aperture; however, the decision as to whether flash light is to be projected or not is conventionally dependent on the subject brightness alone, and does not take advantage of the above-mentioned desirable characteristic of flash photography that the depth of field is enlarged by stopping down the aperture. That is, a greater depth of field makes the focusing function not so strictly dependent on the precision of the autofocus system.